Geotextile Systems Research Articles

Biblometric Analysis of Landslide Slope Stability With Geotextile Reinforement Using Vosviewer

Using biblometrics, this study investigates the relationship between geotextile reinforcement and landslide slope stability. 1000 studies with interrelated topics were created by collecting various studies from 2000 to 2023 using Crossref. Publish or Perish sources were used to run this research network, which was then processed in Vosviewer and saved in Research Information System (RIS) format. The results of the analysis show that slope angle is the most frequently used word and is associated with 63 studies. The results of research conclusion data on the topic of slope stability with geotextile reinforcement continue to increase, with the highest number in 2023 (110 studies).Keyword: Landslides, slope stability, geotextile systems, prediction of landslide management.

Clayey sand–nonwoven geotextile interface characterisation through gradient ratio test

Nonwoven geotextiles have been widely used as a substitute for mineral materials to provide filtration functions in civil engineering. However, in filter systems, geotextiles are the first to be in contact with soft, saturated, and fine soils. For that reason, the selection of a geotextile filter depends on the characteristics of the geosynthetics and the base soil (e.g. grain size distribution, internal stability, permeability) and on the design and boundary conditions such as continuity of the soil–geotextile filter contact interface. The geotextile filter must be properly designed to avoid clogging. The most commonly method used for measuring filtration compatibility of soil–geotextile systems is the gradient ratio test. This paper presents the gradient ratio test program for needle-punched nonwoven geotextile used as a filter layer and internally unstable soil. Laboratory tests were conducted in a modified gradient ratio test apparatus. Test results show that gradient ratio increases with time due to clogging. Also the need for a measurement of water heads very close to the geotextile to measurement of water heads very close to the geotextile to provide additional information on the soil–geotextile system behaviour were presented.

Influence of sand addition in the early stage retention of fine sludge dewatering by geotextile

The need to investigate viable methods to facilitate correct disposal of high-water content waste is immediate in the scenario of water source degradation. In this context, Closed Geotextile Systems (CGS) have shown promise for dewatering a variety of high water-content sediments, aiming to reduce the waste final volume, encapsulating particles, and at the same time allowing fluid drainage. Especially in Water Treatment Plants, the geotextiles generally employed in these systems have good tensile strength and rigidity to support mechanical solicitations and hydraulic properties that warrant good drainage conditions. In these applications, the geotextile element should assure the waste confinement and retention of some particles that will form a filter cake which will control internal flow conditions. The present work investigated how small portions of sand influence fine-particle retention. The sludge used consisted of a mixture of filtered water with two well-defined fractions of ground quartz: FG, a silt and CG, a fine sand. The results show that small amounts of sand are capable of leading to the formation of a pre-filter, even if the maximum diameter of the fine particles is much less than the geotextile filtration opening size. The test results indicate that the retention efficiency gradually increases as CG increases in the solution, up to a fraction of CG close to 14%, which represents only 0.7% of the total solution mass. The increase in particle retention was directly proportional to the increase in the GC fraction until reaching the filtration efficiency of approximately 72% where it stabilizes.

Evaluation of recycled concrete aggregate backfill for geosynthetic-reinforced MSE walls

Mechanical and hydraulic properties of recycled concrete aggregate (RCA) were evaluated for use as backfill in mechanically stabilized earth (MSE) walls. Large-scale drained triaxial tests, direct shear tests and pullout tests were performed to obtain mechanical properties of RCA interacting with various geosynthetics. Long-term filtration (LTF) tests were performed to evaluate hydraulic conductivity of RCA-geotextile systems. Results showed that the RCA had an internal friction angle of 49°, which was within the typical range. The RCA-uniaxial geogrid had the highest interface friction angle of 36° – and the interface friction angles of RCA-biaxial geogrid, RCA-nonwoven geotextile, and RCA-woven geotextile were 32°, 26° and 22°, respectively. Reinforced RCA showed comparable pullout capacity to reinforced sand. No slippage was observed between the RCA and geotextiles or geogrids, and the failures occurred mainly due to rupture of the geotextiles and geogrids during the pullout test. Results of the LTF tests showed that, over a filtration period of 2500 h, the ratio of mean hydraulic conductivity of RCA only to that of RCA-nonwoven geotextile and RCA-woven geotextile systems remained between 0.91 and 3.2, suggesting that the clogging of the geotextiles with RCA was minimal.

Potential of Flocculant-Aided Soil Slurry Dewatering in Land Reclamation: Laboratory Investigations

When soil slurry is used as a fill material in land reclamation projects, vacuum preloading or geotextile tube systems are often adopted for the dewatering treatment in a large scale. However, these two methods often suffer from clogging problems and impede further dewatering treatment. In this study, we test the potential of using flocculants to enhance the dewatering efficiency in a vacuum preloading model test and a geotextile tube model test. Experimental results show that, by adding a flocculant into soil slurry, the dewatering efficiency in terms of drainage volumes and rates is significantly improved as compared to that in pure soil slurry. The amounts of drainage water in the tests with flocculant addition are about 20% and 100% more than those in pure slurry tests in the vacuum preloading and geotextile tube model tests, respectively. The underlying reason could be the flocculation effect that prevents the movement of small soil grains and the formation of impermeable layers on the filters.

Methodology to evaluate hydraulic compatibility of geotextile and RCA in underdrain systems

Long-term filtration tests were conducted to assess the hydraulic compatibility of the recycled concrete aggregate (RCA) and nonwoven geotextile that is typically used in underdrains. The RCA samples used in this study were collected from a single facility, but with different ages (aged in the laboratory). Geotextile samples were also exhumed after each test and evaluated for reduction in their serviceability. The laboratory tests showed that aging does not adversely affect the hydraulic properties of the RCA in long-term filtration tests. The results showed that the previously defined serviceability criteria based on gradient and permeability ratios are not relevant to evaluate the hydraulic compatibility of RCA/geotextile tested in this study due to the existence of turbulent flow regime. An alternative limiting ratio called herein hydraulic conductivity ratio (HCRLFT) is proposed and validated with long-term filtration tests performed with natural aggregates. An acceptance criterion of HCRLFT ≤ 4 is suggested to assess the compatibility of RCA (or natural aggregate)/nonwoven geotextile systems.

Water Flow Through Sand-based Root Zones Atop Geotextiles

An alternative to the time-tested gravel drainage layer beneath a sand-based root zone of a sports field or golf putting green can be constructed from a geotextile atop a highly porous drainage material or structure. The geotextile serves to support the root zone mixture on the drainage layer whose pores can be too large for the sand to support itself by bridging. In such an application, the geotextile should have high enough strength and resistance to stretching to support the root zone mixture atop the pores of the drainage layer and should contain internal pores of appropriate size to retain the bulk of particles in the root zone mixture and to allow free passage of drainage water and eluviating fine particles. The objective of this study was to determine whether geotextiles selected to meet these criteria affect the drainage rates of sand-based root zones and whether they affect the size of particles lost from the root zone–geotextile systems. In a 1-year laboratory study that made use of 150-mm diameter polyvinyl chloride (PVC) test cells, measurements of drainage rates and saturated hydraulic conductivities were made on replicated combinations of 10 geotextiles and three 300-mm deep root zone mixtures. Size distributions and total masses of particles that passed from the root zones through the geotextiles were measured. Statistical analyses showed that drainage rate, saturated hydraulic conductivity, and size distribution and mass of eluviated particles were unaffected by the properties of the geotextiles. The results gave of no reason to prohibit the use of geotextiles to support sand-based root zones in golf putting greens or sports fields.

Effects of Normal Pressure on the Clogging Behavior of Geotextile and Gap-Graded Soil Filtration Systems

The applied loads have a significant role on the filtration property of soil and geotextile systems. This paper investigates the effects of normal pressure on the clogging behavior of geotextile and gap-graded soil filtration systems. The experimental results show that the clogging potential increases as the normal pressure increases. And a critical value for the normal pressure may exist. When the applied normal pressure is less than the critical value, the normal pressure has significant effects on the filtration systems. However, when the applied normal pressure exceeds the critical value, effects of the normal pressure on the soil-geotextile filtration systems are minor.

Testing system for hydraulic properties of unsaturated nonwoven geotextiles

ABSTRACT: The water retention curve (WRC) of unsaturated nonwoven geotextiles is necessary for the prediction of transient water flow in unsaturated soil–geotextile systems. A test method is introduced in this study to measure the WRC of deformable, unsaturated nonwoven geotextiles. This test method combines the axis-translation technique with water flow control using a flow pump. Specifically, a nonwoven geotextile specimen is placed within a flexible wall permeameter atop a cellulose membrane having high air entry and low impedance, and the flow pump is used to impose upward or downward water flow across the membrane. A control loop is used to reach stable suction values at the boundary of the suction in order to ensure that points on the WRC are defined for equilibrium flow conditions. A piston is used to apply a vertical load on the nonwoven geotextile specimen in order to replicate field loading conditions, and was also useful for measurement of changes in specimen volume. The combination of flow control, suction stabilization, and height measurement allow this new approach to effectively consider the impact of normal stress and matric suction on the porosity of the geotextile during measurement of the WRC. Experimental results for typical tests indicate that this approach yields drying and rewetting WRC curves for a geotextile specimen consistent with those in the technical literature.

Numerical parametric investigation of infiltration in one-dimensional sand–geotextile columns

Geotextiles are routinely used in separation and filtration applications. Design of these systems is currently based on saturated properties of the geotextiles and the surrounding soils. However, in the field, soil and geotextile can be in an unsaturated state for much of their design life during which they are essentially hydraulically non-conductive. Periodic wetting and drying cycles can result in rapid and large changes in hydraulic performance of soil–geotextile systems. The writers have reported the results from physical water infiltration tests on sand columns with and without a geotextile inclusion. The geotextile inclusions were installed in new and modified states to simulate the influence of clogging due to fines and to broaden the range of hydraulic properties of the geotextiles in the physical tests. This paper reports the results of numerical simulations that were undertaken to reproduce the physical tests and strategies adopted to adjust soil and geotextile properties from independent laboratory tests to improve the agreement between numerical and physical test results. For example the paper shows that the hydraulic conductivity function of the geotextile must be reduced by up to two orders of magnitude to give acceptable agreement. The lower hydraulic conductivity is believed to be due to soil intrusion that is not captured in conventional laboratory permeability tests. The calibrated numerical model is used to investigate the influence of geotextile and soil hydraulic conductivity and thickness as well as height of ponded water at the surface on wetting front advance below the geotextile and potential ponding of water above the geotextile due to a capillary break mechanism. A simple analytical model is also developed that predicts the maximum ponding height of water above the geotextile based on two-layer saturated media and 1-D steady state flow assumptions. The analytical model is used to generate a design chart to select geotextiles to minimize potential ponding of water above the geotextile. Ponding can lead to lateral flow of water along the geotextile in reinforced wall, slope, embankment and road base applications.

State-space solution of seabed–geotextile systems subjected to cyclic wave loadings

Analytical solutions for dynamic responses of seabed–geotextile systems subjected to cyclic wave loadings are presented in this paper, which contains the solutions of the transient and harmonic responses. The theory is based on the Biot consolidation equations in which the pore fluid as well as the soil skeleton is considered compressible and the flow in the porous seabed is assumed governed by Darcy's law. The present analysis is completely based on the state-space formulations, which is very effective for laminated systems analysis. Together with Laplace–Fourier transform techniques, state-space methods are used to solve the governing equations. Responses of seabed–geotextile systems can be calculated by using the matrix theory, boundary conditions and inverting integral transform. As illustrative examples, laboratory experiments, which conducted at the Oregon State University Wave Research Facility in USA by McDougal [1981. Ocean wave–soil–geotextile interaction. Ph.D. Dissertation, Oregon State University], are analysed. It is shown that the numerical results are in good agreement with those obtained from laboratory experiments, and the distinction between the transient and harmonic response should be taken into account for design of marine geosynthetic systems. Under the transient condition, the seabed is apt to liquefy. Seabed stability may be increased by placing geotextile beneath an armour layer. The numerical evaluations of the solution in the seabed–geotextile systems can be easily achieved with high efficiency and accuracy.

Soil–geotextile filter interaction under high stress levels in the gradient ratio test

This paper presents the results of gradient ratio tests on different soil–geotextile systems under normal stresses up to 2000 kPa. Different types of soil and geotextiles were tested, and the soil particles that passed through the geotextile and those retained in it were collected for particle size analyses. The results obtained show that the use of definitions of gradient ratio based on the measurement of water heads close to the geotextile layer can be useful for a better identification of geotextile-clogging mechanisms. The entrapment of soil particles in the geotextile increases its retaining capacity and alters the conditions for further clogging. The dimensions of the entrapped soil particles can be greater than the geotextile pore dimensions under unconfined conditions and are controlled by soil and geotextile characteristics and by the soil sample preparation technique employed. The results suggest that current retention and permeability criteria for geotextile filters can be excessively conservative. Discussions on geotextile performance in the test and under field conditions are also presented as well as limitations and new proposals for the interpretation of the gradient ratio test.

Quantifying hook and loop interaction in textured geomembrane–geotextile systems

This paper examines the role of geomembrane texture on geomembrane–geotextile interface performance, focusing in particular on hook and loop interaction. The study specifically involves textured HDPE geomembranes and needle punched nonwoven fabrics; however, the concepts presented may be relevant to other geosynthetic systems. The effects of hook and loop interaction on geosynthetic interface performance were quantified through laboratory interface shear testing, ASTM hook and loop interaction tests, and optical microscopy. Testing was conducted over a large range of normal stresses (0.4–312 kPa) to capture variations in behavior as a function of normal stress. Results show that the magnitude of hook and loop interaction depends on the characteristics of the geomembrane texture and can contribute a significant portion of the peak interface strength. The results aid in quantifying behavioral differences observed between geomembranes textured using different manufacturing processes, and provide microscale insight into textured geomembrane–geotextile interaction mechanisms over a range of stress levels.

Filtration Performance of Woven Geotextiles With Wastewater Treatment Sludge

Capping of contaminated soft sediments and sludges for in situ containment provides an efficient remediation alternative. Capping design typically involves the use of geosynthetics for multiple functions, e.g., reinforcement, separation, and filtration. Filtration performance becomes a decisive factor for proper long-term performance of a cap. Because of multiple functions required, woven geotextiles are often the choice geosynthetic in such applications. A research program concerning the filtration behavior of contaminated wastewater treatment sludges was conducted. The laboratory portion of the program included a series of filtration tests with different woven geotextiles. Filtration performance of the sludge-woven geotextile systems was also observed in field test cells. Geotextile samples were exhumed from the cells after exposure and analyzed in the laboratory. The results indicate that the sludges can be filtered using woven geotextiles and the selection of a proper filter can be made on the basis of geotextile pore structure parameters, i.e. percent open area and pore opening size distribution. The standard gradient ratio test did not always reflect the filtration performance and, therefore, other clogging ratios need to be considered. A commonly used geotextile pore opening size-to-soil particle ratio in the existing filter criteria, O95/D85, did not predict the filtration behavior displayed by the sludge; however, another ratio, O50/D 50 , showed general correlation to clogging and retention.

A study on the behaviour of soil–geotextile systems in filtration tests

The behaviour of soil–geotextile systems in filtration tests is reported for nonwoven geotextiles under unidirectional flow. A new apparatus was developed to preform filtration tests under an applied vertical stress, and tests were then conducted with different soils and nonwoven geotextiles in order to evaluate the clogging potential and retention capacity of these materials under rather severe combinations of geotextile and soil characteristics. Results show that the geotextiles perfomed well and that observed permeability losses were acceptable even for gradient ratios close to 3. No progressive piping was observed, and it is believed that the retention capacity of the geotextiles may be influenced by their manufacturing process. In general, theoretical predictions for the maximum particle size passing through the geotextile compared well with measurements. Key words: geotextiles, filtration, gradient ratio, permeability, soil retention, clogging.

Theory of Soil / Geotextile Interaction

In this study, soil/geotextile interaction is characterized by the following general equation- τ = τa + tan δ*( σnor) n-where τ and σnor are shear and normal stresses on the failure plane at failure, τa is the soil/fabric adhesion component, and δ* and n are friction indexes. This equation provides a general relationship in which the classical Mohr-Coulomb law is considered as a special case. It holds for a wide range of normal stresses and describes soil/geotextile interaction in terms of material-related parameters. A theoretical interpretation of the effects of critical factors affecting soil / geotextile interaction is based on this equation. The four main factors examined are soil/geotextile adhesion, normal stress, deformation of junctions at the soil/fabric interface, and surface roughness. To evaluate interactive deformational modes of soil / geotextile systems, a pull-out test device was designed and constructed and used to test woven and nonwoven textiles. Identified interactive modes were divided into three main categories: pure slippage, complete rupture, and combined slippage and longi tudinal deformation. This categorization supported by the equation above can help rationalize the complex mechanism involved in pull-out conditions.